Proto-oncogenes play a critical role in the regulation of cell growth, but it has been difficult to relate the structure of these molecules to their biological functions within the cell.. The goal of this proposal is to determine the role of several critical proto-oncogenes in the control of cell division. In past work a neutralizing antibody to the proto-oncogene ras was identified and microinjected into living cells. The consequences of this treatment upon the proliferative capacity of the cell then indicated the function of ras proteins in normal proliferation. It was clear not only that cellular ras proteins were critical for proliferation, but that ras activity was essential to the function of some but not all retroviral oncogenes. On the basis of these results we have suggested that ras proteins might function to transmit a proliferative signal from one class of proto-oncogenes to another, and that phospholipid metabolism is involved in this signalling. The objective of this proposal is to test these critical hypotheses. First, neutralizing antibodies to other proto-oncogenes believed to function at different stages of the postulated signal transduction pathway will be produced and tested. These antibodies will allow a direct test of the hypothesis that various proto-oncogenes function together in a signal transduction pathway. In addition, previous studies with the anti-ras antibody suggested that phospholipid metabolism might be involved in regulating the biological activity of ras proteins. Recent studies have provided direct biochemical evidence that this might be the case. If these results can be verified and expanded it might provide the first indication of how the activity of cellular ras proteins might be controlled during mitogenesis. The second objective of the proposed study is, therefore, to verify and expand these initial studies. The importance of this work is emphasized by the fact that while cellular ras proteins are believed to play a central role in the control of proliferation, no other indication has yet been reported to explain the biological activation of these proteins. Finally, these microinjection and biochemical studies will be placed in a biological context. The action of oncogenes will be placed in temporal relationship to the known biological marker of cell division . These studies constitute a unique approach in the biological analysis of proliferative genes. the information obtained will undoubtedly aid directly in a molecular understanding of tumor formation since these genes are among those most often mutated in natural human tumors. Furthermore, the biological markers to be tested included antiproliferative agents commonly utilized in anti-tumor therapy.